Field of the Invention
The invention relates generally to fluid pumping technology and more specifically to a cassette pump having a multi-laminate membrane with magnetic and/or conductive properties that attaches to pumping fingers through electrostatic or magnetic forces.
Background Information
Cassette pumps provide a convenient and relatively low cost device for infusing drugs into the body of a patient. These pumps employ cassettes made of injection molded plastic, which are discarded after use with a patient. A pump designed to operate with a particular configuration of cassette includes a drive mechanism that actuates the cassette to deliver fluids to a patient. Such pumps are typically controlled by a microprocessor that can be programmed to deliver a predefined volume of medicinal fluid, at a predefined rate, and over a predefined time. Cassette pumps are typically more accurate than peristaltic pumps and are able to deliver drugs at a relatively wide range of rates and volumes.
There have been no significant breakthroughs in large volume perenteral (LVP) pumping mechanisms since the first cassette and peristaltic pumping systems were introduced over 30 years ago. Large volume infusion pumps on the market today are products of an evolutionary process of iterative design, evolving from the vented glass bottle and roller clamp controlled drip rate through electronic drip counters, controllers and finally volume displacement pumps. Thus, advances in the industry have been incremental system refinements at best, having more to do with improvements in motor control software that leverage advancements in sensor technology to compensate irregular mechanical pumping performance with complex software motor drive algorithms. Software control has driven steady improvements in instrument accuracy and flow uniformity over the years; however since the fundamental pumping mechanisms have not changed, inherent weaknesses remain. The difficulties that these pumping systems have always had in accommodating high fluid viscosities, wide ranges of infusion rates, variations in differential pressure, and a variety of other use conditions, have not been addressed.
Performance related issues fall into four general categories; system compliance, component tolerance sensitivity, dimensional stability of the disposable/instrument interface and the serial nature of the peristaltic and single chamber pumping systems. Errors induced by electronic hardware tolerances and software control are relatively small and are outside the scope of this invention. Thus, the invention relates to Large Volume Perenteral (LVP) infusion devices and addresses inherent issues with current traditional systems which influence the overall performance of fluid delivery.